Street art, from graffiti to posters, stickers and stencils, is one of the most popular aspects of the mainstream contemporary art scene, commanding high prices at auction. Banksy and Futura 2000 are widely written and commented on. From its association with the music scene and hip-hop culture in particular, street art has offered a path to gallery and commercial success for artists such as Warhol’s collaborator, Jean-Michel Basquiat, or Keith Haring with his ‘subway drawings’. David Cameron gave a book of graffiti art to President Obama. It has even been taken up as advertising by corporations such as IBM and Sony. French 123Klan produce logos and designs for the likes of Nike and Coca Cola: something that may give the lie to Banksy’s pronouncement that, ‘You can make more money producing a run of anti-McDonald’s posters than you can make designing actual posters for McDonald’s’. There is something of a fashion today for corporate anti-corporatism.

Yet, there is a long tradition of radical political graffiti, which was wittily fictionalised in the ‘Romanes eunt domus’ of Monty Python’s Life of Brian, and more starkly instantiated by the ‘Troops out’ slogans and murals of the conflict in Northern Ireland. In the Second World War, the French resistance risked their lives to daub ‘V’ for victory and ‘RAF’ over Nazi and Vichy posters. The anodyne postwar craze for ‘Kilroy was here’ soon gave way to the rebellious subcultures of the late 1960s and 1970s. In Amsterdam, situationists and Provos covered the city with tags like ‘Dr Rat’ and ‘Klass is coming’, while French students in 1968 preferred formulations like ‘L’ennui est contre-révolutionnaire’. Americans followed suit with ‘Dick Nixon before he dicks you’ and ‘Free Huey’. The punk band Crass started political stencilling in 1977, with slogans such as ‘Stuff Your Sexist Shit’ in London tube stations.

While tagging in Singapore can still get you imprisoned rather than feted, is there an argument that the dissident street writing of yesterday has become the new normal, even high art? Is Banksy’s ‘Piss Alley’ Cans Festival (slogan ‘Gentrify This’) the National Gallery or Southbank Centre of today? Seemingly more public and more radical than sanitised museum collections, but possibly in danger of losing its edge? Has it become harder to see just what it is that contemporary graffiti artists are railing against? If street art has taken its place as worthy of equal respect alongside Vermeer and Magritte, where do today’s angry youth go for self expression? Has urban discontent become safe artistic commodity, or does it still épater le bourgeois and demand a better tomorrow?

Government-financed brigades of graffiti artists and muralists are blanketing this city’s walls with politicized images, ranging from crude, graffiti-tagged slogans to bold, colorful works of graphic art.

This is a lavishly illustrated insider's guide to street art that is both global in scope and in touch with local scenes. Featuring rare interviews with leading practitioners of the last thirty years, it includes work by artists such as Banksy, Blek le Rat, Futura 2000, Miss Van and Os Gemeos.

Graffiti and street art have long existed as a safety valve for individuals to vent their anger and frustration, whether in the form of scrawling angry messages on bathroom stalls or pasting posters on the windows of government buildings. But it is when the vast majority of people begin to feel that they have no other outlet to communicate, that the media channels open to them are uni-directional and they are on the receiving end of a string of lies and half truths, that street art can act as an antidote to our visual space being used as a social control mechanism.

Here's a mystery for you. Renegade urban graffiti artist Banksy is clearly a guffhead of massive proportions, yet he's often feted as a genius straddling the bleeding edge of now. Why? Because his work looks dazzlingly clever to idiots